Barack Obama stands next to Sonia Sotomayor, his pick for supreme court justice, in the East Room of the White House. Photograph: Saul Loeb/AFP

In Sonia Sotomayor, Barack Obama has chosen for the court a safe liberal voice whose legal thinking was informed by her upbringing in a rough area of the Bronx borough of New York, and who was inspired to enter law by a television courtroom drama and the exploits of a fictional teen detective.

Sotomayor, 54, brings an impeccable legal resume that will make it difficult for Republicans to attack her credentials, and a compelling personal background that Obama said colours her legal philosophy with empathy and understanding for downtrodden Americans. She is the first Hispanic nominee to the court, and if she is confirmed would be only the third woman.

"This wealth of experiences, personal and professional, have helped me appreciate the variety of perspectives that present themselves in every case that I hear," she said today. "It has helped me to understand, respect and respond to the concerns and arguments of all litigants who appear before me, as well as to the views of my colleagues on the bench. I strive never to forget the real-world consequences of my decisions on individuals, businesses and government."

Sotomayor has served on the federal bench for 17 years, giving her more judicial experience than any supreme court justice confirmed in the past seven decades. She also has a bipartisan pedigree, appointed by a Republican president, George Bush Sr, to a federal district court in 1992, and by Democrat Bill Clinton to the court of appeals, based in New York, in 1997.

US supreme court appointees must be confirmed by the Senate. Although the body is controlled by Obama's Democratic party, the Republican minority could aggressively question her. But Sotomayor has already been confirmed to the federal bench twice by the Senate.

"At the end of the day it's awful hard to beat back someone with her credentials," veteran Republican strategist Ed Rollins told CNN. "My sense is it'll turn out to be a brilliant choice."

The daughter of Puerto Rican immigrants, Sotomayor grew up in public housing in the south Bronx. She was diagnosed with diabetes at age 8, and her father passed away when she was nine years old. Sotomayor found solace in the Nancy Drew series of teen detective novels, and the television courtroom exploits of Perry Mason, which inspired her to enter law.

Sotomayor was reared by her mother, who had bought the only set of encyclopaedias in the neighbourhood. She attended Catholic school, and like the sitting supreme court justices, later graduated from elite universities. She earned her undergraduate degree at Princeton, then graduated from Yale law school.

She began her legal career in 1979 as a prosecuting attorney in New York City. In 1984 she joined a prominent New York corporate law firm, focusing on intellectual property issues, and international litigation and arbitration.

Sotomayor has a record of liberal rulings in high profile decisions. In a ruling the supreme court is likely soon to overturn, she found against a group of white Connecticut fire-fighters who claimed the city had discriminated against them in an effort to promote blacks. In 1995, she ruled in favour of striking professional baseball players, ending an impasse that had cut short the 1994 baseball season.

But she has also ruled several times on the side of law enforcement, which in American jurisprudence tends to be the conservative side of an issue. She ruled in two cases that police and the FBI could use evidence obtained under an improper or invalid search warrants.

When justice David Souter announced he would retire from the court, Obama indicated he would seek a nominee who brings to the bench an ability to empathise with people's daily struggles, rather than treat law and justice as mere application of abstract legal theories.

"It is experience that can give a person a common touch and a sense of compassion - an understanding of how the world works and how ordinary people live," Obama said today. "And that is why it is a necessary ingredient in the kind of justice we need on the supreme court."